Bug 989349 - part 2 - eliminate static constructor in GLContextProviderGLX.cpp; r=bjacob

gfx/gl/GLContextProviderGLX.cpp

@@ -1190,14 +1190,20 @@ GLContextProviderGLX::CreateOffscreen(const gfxIntSize& size,
 }
 
 static StaticRefPtr<GLContext> gGlobalContext;
-// TODO move that out of static initializaion
-static bool gUseContextSharing = getenv("MOZ_DISABLE_CONTEXT_SHARING_GLX") == 0;
 
 GLContext*
 GLContextProviderGLX::GetGlobalContext()
 {
+    static bool checkedContextSharing = false;
+    static bool useContextSharing = false;
+
+    if (!checkedContextSharing) {
+        useContextSharing = getenv("MOZ_DISABLE_CONTEXT_SHARING_GLX") == 0;
+        checkedContextSharing = true;
+    }
+
     // TODO: get GLX context sharing to work well with multiple threads
-    if (!gUseContextSharing) {
+    if (!useContextSharing) {
         return nullptr;
     }